Fuel tank ventilation in motor vehicles

ABSTRACT

A motor vehicle fuel tank having at least two spaced apart holes on its surface with each of the holes being connected to a fuel vapor trap. To prevent liquid fuel from leaving the tank and entering the trap, each hole is controlled by a float valve connected between the hole and the trap.

United States Patent Torazza [451 Aug. 22, 1972 [54] TANK VENTILATION INMOTOR [56] H References Cited v CLES UNITED STATES PATENTS [72]Inventor: Giovanni Torazza, Turin, Italy 2,414,158 1/1947 Mock ..l23/l19R X [73 l Assignee: Fiat Societa Per Azioni, an Italian 3,542,23911/1970 Latvlala 2 VR Joint Stock Company Turin Sarto .J. l [22] Filed:Primary Examiner-Laurence M. Goodridge [21] Appl. No.: 88,748Attorney-Sughrue, Rothwell, Mion, Zinn &'Macpeak [30] ForeignApplication Priority Data [57] ABSTRACT 14 4 A motor vehicle fuel tankhaving at least two spaced Nov 1969 Italy S 032 A169 apart holes on itssurface with each of the holesbeing 52 US. Cl. ..l23/l36, 220/85 VR, 123121 Connected to a fuel vapor p- TO Prevent qu fuel 51 1m. (:1 ..F02m59/00 from leaving the tank and entering the trap, each hole- [58] Fieldof Search ..'...l23/l 19 R, 136, 120; i ntrolled by-a float valveconnected between the 220/85 VR hole and the trap.

2 4 Figures Patented Aug. 22, 1972 3,685,504

3 Sheets-Sheet 1 Patented Aug. 22, 1972 v 3,685,504

' s Sheets-Sheet 2 Patented Aug. 22, 1972 3,685,504

5 Sheets-Sheet s I FUEL TANK VENTILATION IN MOTOR VEHICLES Thisinvention relates to the ventilation of the fuel tank of a motorvehicle.

Research on atmospheric pollution has shown that it is highly desirableto prevent the'escape of fuel vapor from the tank to the atmosphere.Legislation has been introduced in the United States of America to makeit compulsory in certain areas to have a trap preventing the escape offuel vapor from the tank, and various forms of trapping systems havebeen proposed.

Among the forms proposed, it is common to have a fuel tank with aplurality of holes in its upper surface, spaced apart from each other sothat in any condition of the vehicle during normal driving, and with thetank filled to the maximum, at least one of the holes is free from fuel.All the holes are connected by separate tubes to a container whichshould be located sufficiently high above the tank to ensure that thecontainer will never be flooded with liquid fuel during normal driving.The container acts as a manifold, being connected by a duct to a trapcanister containing a fuel vapor trapping material such as activatedcarbon. Air is circulated through the canister to draw fuel vapor out ofthe trap and into the air stream feeding the engine. A valve that isnormally closed to the atmosphere is inserted in the system to allow theentry of air from the atmosphere when there is an under-pressure in thetank. The valve also allows gas to escape from the tank to theatmosphere in the event of a dangerous and sudden over-pressure, causedby an event suchas collapse of the tank in a collision.

When the vehicle is unused for a substantial period, vapor collects inthe trap and is purged by air circulating through it when the engine isnext started.

With a vapor trap system such as this, it is essential to prevent fuelin liquid form from reaching the trap since it would render the trappingmaterial useless. For this reason the manifold should be as high aspossible above the tank. However, practical considerations set a limiton this height, particularly when the fuel tank is in any event directlybelow the bonnet of an automobile.

An object of the invention is to alleviate this problem and make itunneccessary to have a tall space above the fuel tank to receive thetubes.

The invention provides a motor vehicle having a fuel tank with aplurality of holes spaced apart in its upper surface, a tube leadingfrom each hole, a fuel vapor trap with which each tube communicates,purging means to pass air through the trap, an engine to which thepurging air is fed, and normally closed valve means to control thecommunication of the tank with the atmosphere; characterized by a valvecontrolling the flow of fluid through the tube at each hole, the valvepermitting the outflow of vapor from the tank but preventing the outflowof liquid fuel.

The valve at each hole is preferably a float valve.

In the drawings:

FIG. 1 illustrates diagrammatically arrangements according to theinvention for ventilating the fuel tank of a motor vehicle;

FIG. 2 is a plan view of a detail of FIG. 1;

FIG. 3 is a section on the line III-III of FIG. 2; and

FIG. 4 is a section on the line IV-IV of FIG. 2.

In FIG. 1, a motor vehicle has an engine 1 supplied with fuel from atank 2. The tank is elongated, its axis being substantially horizontal.For filling, the tank has a tube 5 connected to a side wall 3 and closedby an airtight cap 6. The tank is connected by ducts not shown to acarburetor 7 of the engine.

At opposite ends of the upper surface 4 of the tank 2 are float valves 8to be described in detail later. Each valve 8 is connected by a branchtube 44 to a tube 45 which leads to a valve 52 of known construction,which admits air from the atmosphere when there-is an underpressure inthe tank 2 and which, in cases of a sudden extreme over-pressure in thetank, caused by an event such as a collision crushing the tank, allowsvapor from the tank to escape to the atmosphere. For a slightoverpressure in the tank, the valve 52 allows vapor to pass from thetube 45 to a tube 51 leading to a fuel vapor e trap 46, also of a knowntype. The trap 46 contains a vapor-absorbing material such as activatedcarbon. The

trap is connected by a tube 47 to the outlet 48 of an air filter, toallow clean air to enter the trap and purge it. The purging air leavesthe trap through a tube 49 which leads to the intake manifold of thecarburetor 7.

The valves 8 control holes at the ends of the tank, permitting theoutflow of vapor but not of liquid-fuel. One hole will be open whateverthe inclination or other conditions of the vehicle during normaldriving, sothat I there will always be a passage for vapor from the tank2 to the trap 46. Liquid fuel, however, cannot pass fro the tank.

Details of the valves 8 are seen in FIGS. 2 to 4. Each valve 8 isconnected to the tank 2 by means of a bracket 9 (FIGS. 3 and 4), and hasan interior chamber 10 closed by a cover 12 secured by bolts l5.to aflange 11 on the body of the valve. A lower hole 17 (FIG. 2) in the bodyof the valve is connected by a tube 19 to a hole 18 (FIG. 3) in thetank. An upper hole 21 (FIG. 4) in the valve body is connected by a tube22 to a hole 23 in the tank. The tubes 19 and Hand the holes theyinterconnect are of small cross-section in order to retard the flow ofliquid fuel into the chamber 10.

The cover 12 is substantially horizontal and has a holes 30 and 31. Theholes 30, 31, 27, 26,25 form a passage passing through the cover 12.This passage is controlled by a closure member 35 in the form of acylindrical body having an upper conical tip 36. The body 35 slides withradial clearance in the hole 30, the tip 36 closing the hole 31 when thebody 35 is in its uppermost position. A float 37 is connected to a lowerarm 42 of a rocking lever which is pivoted by a horizontal pin 39 to twolugs 38 projecting downward from the cover 12. An upper arm 41 of therocking lever is connected to the lower end of the body 35 to move it upand down between a closed and an open position.

A short tube 43 is mounted in the hole 25. on the outside of the cover,and is in turn connected to a tube 44 (FIG. 1) leading vapor away fromthe tank 2.

Liquid fuel leaving the tank 2 through one of the are restored in thetank. While one of the valves 8 is closed, the other will be open topermit the outflow of vapor. v Withthe ventilation arrangements of theinvention,

the tubes 44, 45 can communicatedirectly with the vapor trap 46- withoutthe need for a container.

mounted in a raised position to accommodate liquid rising up the tubesfrom the tank, such a container having been commonly provided in priorsystems.

The valves 8 are mounted sufficiently high relatively to the tank 2 thatwhen the vehicle is'stationary and not sloping unduly liquid fuel willnormally not enter the chambers 10 to raise the floats 37 even when thetank is full.

lclaim:

l. A motor vehicle having an elongated fuel tank arranged with its axissubstantially-horizontal, two holes at each end of the tank in its uppersurface, a float valve positioned at each end of the tank adjacent thetwo holes thereat, the two holes at each end being connected atdifferent vertical levels to a chamber of each float valve, the floatvalve having a passage controlled by a closure member, the passage beingconnected by a branchtube to a similarbranch tube connected to the floatvalve at the other end of the tank, the branch tubes being connected toa normally closed control valve whichunder a slight over-pressure in thetank permits the passage of vapor through the control valve, and whichopens to admit air from the atmosphere when there is an under-pressurein the tank, the control valve being connected by a tube to a fuel vaportrap, the trap being connected to a source of filtered air for purgingof the trap and being connected to an air intake of the vehicle engineto receive the purging air leaving the trap, the float valves beinglocated at a level above the tank such that the float valves are openwhen the 4 7 vehicle is stationary and substantially horizontal, eachfloat valve passage having a substantially vertical portion and theclosure member being mounted for move-' ment in a substantially verticaldirection in that passage, the float member being attached to'an arm ofa lever mounted for rocking movement about a sub stantially horizontalpivot fixed in the chamber of the float valve, the rocking lever havinga second arm to which is attached afloat member. r

2. In a motor vehicle having a liquid fuel tank provided with a vaporventilation means, a fuel vapor trap connected by a tube to theventilation means, purging means for passing air through the trap, anengine to which the purging air is fed, and normally closedvalve meansconnected between the ventilation means and the vapor trap tocontrol thecommunication of the positions, said openings being above the normalmaximum level of fuel in the tank when the vehicle is stationary andsubstantially level;

b. valve means positioned adjacent to each of said 0 ni ac valve m iludin a ve h usin g thi iri terior of each v ve h g e r ng connected toone of said conduit means; a vapor outlet passage extending through anupper wall of said housing and connected to said tube; a valve seat insaid passage; a a valve closure member movable in said passage to abutsaid seat and close said passage; and p i f. a float member rnovablycontained in said housing and operatively connected to said valveclosure member and located above said normal fuel level, whereby inflowof liquid fuel through each of said conduit means to said housing actson said float member to close said valve passage to prevent flow ofliquid fuel through said tube. I

1. A motor vehicle having an elongated fuel tank arranged with its axissubstantially horizontal, two holes at each end of the tank in its uppersurface, a float valve positioned at each end of the tank adjacent thetwo holes thereat, the two holes at each end being connected atdifferent vertical levels to a chamber of each float valve, the floatvalve having a passage controlled by a closure member, the passage beingconnected by a branch tube to a similar branch tube connected to thefloat valve at the other end of the tank, the branch tubes beingconnected to a normally closed control valve which under a slightover-pressure in the tank permits the passage of vapor through thecontrol valve, and which opens to admit air from the atmosphere whenthere is an under-pressure in the tank, the control valve beingconnected by a tube to a fuel vapor trap, the trap being connected to asource of filtered air for purging of the trap and being connected to anair intake of the vehicle engine to receive the purging air leaving thetrap, the float valves being located at a level above the tank such thatthe float valves are open when the vehicle is stationary andsubstantially horizontal, each float valve passage having asubstantially vertical portion and the closure member being mounted formovement in a substantially vertical direction in that passage, thefloat member being attached to an arm of a lever mounted for rockingmovement about a substantially horizontal pivot fixed in the chamber ofthe float valve, the rocking lever having a second arm to which isattached a float member.
 2. In a motor vehicle having a liquid fuel tankprovided with a vapor ventilation means, a fuel vapor trap connected bya tube to the ventilation means, purging means for passing air throughthe trap, an engine to which the purging air is fed, and normally closedvalve means connected between the ventilation means and the vapor trapto control the communication of the tank with the atmosphere, theimprovement in the vapor ventilation means comprising: a. conduit meansconnected to openings in the upper wall of the tank in at least tworemotely spaced positions, said openings being above the normal maximumlevel of fuel in the tank when the vehicle is stationary andsubstantially level; b. valve means positioned adjacent to each of saidopenings, each valve means including a valve housing, the interior ofeach valve housing being connected to one of said conduit means; c. avapor outlet passage extending through an upper wall of said housing andconnected to said tube; d. a valve seat in said passage; e. a valveclosure member movable in said passage to abut said seat and close saidpassage; and f. a float member movably contained in said housing andoperatively connected to said valve closure member and located abovesaid normal fuel level, whereby inflow of liquid fuel through each ofsaid conduit means to said housing acts on said float member to closesaid valve passage to prevent flow of liquid fuel through said tube.